456 SUB-PHYLUM UROCHORDA OR TUNICATA. 
ganglionic mass above the mouth, and a dorsal nerve-cord extending 
backward from this into the tail, where it is furnished with other 
ganglia. In connection with the cerebral ganglion there is a pigment 
spot, an otocyst (auditory ?), and a tubular process communicating with 
the pharynx, and corresponding to the sub-neural gland and the ciliated 
duct of other Tunicates. We have already noted the simple structure 
of the pharynx, which has but two gill-slits communicating directly with 
the exterior. The same simplicity of structure is observable in the 
heart, which is without any associated vessels. The hermaphrodite 
7? 
oe 78 
- ae ot iz 
ov 
— 
br 
ors SO 
st 2x 
if ieee 
. Nat - : end 
app 
les ee 
<n va et! 
a 72 
72R' 
Fic. 247.—Anatomy of Appendicularia.—After 
Ferdman. 
5.0.5 Sense organ ; 47., branchial aperture ; a/., dorsal tubercle ; of., 
otocyst; #.g., nerve ganglion; Ag., peripharyngeal band ;  , 
nerve-cord ; @., cesopbagus ; sf., stomach; ov., ovary; /es., 
testes; 7., intestine ; 4., heart; #., urochord, cut at w’.5 2.¢’., 
mg"., nerve ganglia of tail; ., muscle band ; af¢., tail cut 
theaugh a., anus ; @z., one of the atrial apertures ; evd., endo- 
style. 
reproductive organs lie posteriorly, and open to the exterior by a 
very fine duct on the dorsal surface. As contrasted with Sa/sa and 
Dotiolum, the animals are protandrous, and not protogynous. The 
development is unknown. 
Classification.— 
Order 1. LARVACEA 
Free-swimming, pelagic, and solitary forms provided with a large 
locomotor tail containing a notochord. The pharynx opens to the 
